1. Field of the Invention
The present invention is in the field of multi-stage pumping systems particularly designed for use with modern jet aircraft engines. It includes a centrifugal pump which characteristically has a long life and a positive displacement pump to meet cranking suction requirements.
2. Description of the Prior Art
As gas turbine engine technology advances, the requirements for engine accessories such as engine pumps are considerably more demanding. Engine manufacturers now require engine pumps which are light, compact, very efficient, capable of operating with contaminated and low lubricity fuels, long-lasting, reliable, easy to maintain and inexpensive. Experience with conventionally designed engine pumps such as positive displacement, gear or vane, or variable displacement vane pumps has demonstrated that conventional designs are not capable of meeting the ultimate demands of the aircraft engine industry.